How do you adjust the hydraulic lifters?

No provision for manual valve lash adjustment...'hydraulic' lifters!.. Replace worn or failed parts... Usually the lifter but needs to be inspected... Lifters 'can' be difficult to remove from bore in cylinder head..( best I can remember).. It's been a few years... This used to be fairly common problem but some oil additives may help.. Seafoam motor tune is one example.

No adjustment available